Eliza Wilson, 16, of Fishers, didn't realize she had a heart defect until on spring break when her heart rate skyrocketed to 200 BPM. Her mother, Greta, rushed her to the hospital where it was discovered Eliza had Supraventricular tachycardia.(Photo: Greta Wilson/COURTESY PHOTO)

No one would have guessed Eliza Wilson, who is an avid tennis player and diligent student, had trouble with her heart.

The 16-year-old Fishers native said she could remember her heart "sometimes missing a beat" since birth. She would go through spurts of getting heart flutters, heart stuttering out of beat for a moment, and the feeling would cease in a matter of seconds.

She thought it was normal because it was her normal.

"I started to really notice the flutters around 13-, 14-years-old," Eliza said. "My heart would skip a beat and then the feeling would go away. I never really thought much of it."

Then came spring break 2018.

Eliza and her mother, Greta Wilson, were vacationing in Texas when Eliza said she felt her heart beat differently than it usually did. She remembers sitting down on a bench to take a photo and suddenly feeling as if her heart were skipping in her chest. She wrote it off as one of her usual flutters.

But instead of subsiding after a few seconds, it continued — and would continue for the next five hours. Greta joked that, in the moment, she thought Eliza was faking the heart issue to get out of going on a hike they had planned.

The two drove from Austin back to their San Antonio hotel. When the feeling persisted , Greta instructed Eliza to try lying down for awhile.

When it still didn't improve, Greta had the idea to put her Fitbit on Eliza to see if she could get a reading of her daughter's heart rate. It was when Greta pulled up the monitor on her phone that she began to worry.

A normal resting heart rate is around 100 beats per minute. Eliza's heart rate was clocking in at more than double that, shooting up and down between 220 and 250 beats per minute.

Eliza said she remembered thinking she was going to die.

"At this point I didn’t want her to get nervous, but I was sitting in the other room on the Fitbit app watching her heart rate go crazy," Greta said. "As I was driving (Eliza) to the E.R., we just kept asking ourselves 'How did we get here? Why did this happen today'?”

Though she didn't know it, Eliza was born with Supraventricular tachycardia: a defect that causes a faster-than-normal heart rate due to an error in electrical impulses. The defect is fairly common. Around 200,000 people are effected per year.

Most people with SVT don't realize they have the defect. Either the flutters are so inconsistent that patients don't realize they have it or patients are aware of the continued flutter but, because they are non-lethal, they don't seek treatment.

For most of her life, Eliza fell into the latter half of the population effected by SVT, though she didn't know the name of the defect until her incident in Texas.

Dr. Adam Kean, a pediatric cardiologist and electrophysiologist with IU Health, said self-monitoring using devices such as Fitbits is growing more common.

"We're living in a burgeoning age of individuals taking on a greater responsibility or interest in trying to diagnose and treat themselves,” he said. "In terms of making a clear cut diagnosis (based on an application), the technology is somewhat limited."

A Fitbit can track heart rates, he pointed out, but the device doesn't necessarily know if that heart rate clocks in at a 'good' or 'bad' level. If one were to drop a brick on a person's foot, the Fitbit would pick up an increased heart rate due to an increase in adrenaline. But the uptick in base rhythm wouldn't mean much because the body is reacting to a stimulus.

SVT patients sometimes go months or years without experiencing an episode, Kean said. While Fitbit users can look back at their heart rate, as the device doesn't delete old data, Kean said one must factor in for user error. Just because a spike in heart rate is shown doesn't necessarily mean it's related to SVT.

If patients don't remember why their heart rate spiked in that particular moment, people can trick themselves into believing their SVT is more pressing than it might actually be.

So patients shouldn't conflate data gathered from an at-home device with receiving a real diagnosis from a doctor.

Kean did acknowledge, however, wearing a device like a Fitbit certainly beat having to wear a comprehensive heart monitor for months on end in order to track irregularity in heart rhythms.

Regardless of reliability, Eliza said she wears one constantly now. Since coming home from San Antonio, she's had a procedure that froze and deadened tissue within her heart that caused the irregular beating. She goes back for a check-up in early August that will determine if the procedure worked to the degree doctors hoped, or if further surgery is needed.

Eliza still experiences the flutters, albeit far less than she did before. When she does experience the feeling now, she said it's different and less urgent.

"Little by little, she’s coming back to regular activities," Greta said. "Eliza is getting stronger all the time and the goal is to live life normally from here on out."

This article has been updated to amend the portion talking about Fitbit backup data. Users who have a Fitbit may access any heart rate data they have since the very beginning of using the device.